What do you mean "where did the cloth come from?"? Do you wear pants that have pockets? Do you assume that characters in these movies might not carry things in their pockets? You could ask "where did the multi-pass come from?" or "where did korben's driver's license come from?" People have pockets.... and generally, old people carry hankercheifs. The movie is excellent, don't ask stupid questions.

Sweat is basically water, no matter how much of whatever is mixed with
it. As long as it drips, it counts. You might as well say that there is
no water in the Dead Sea, or the Great Salk Lake, in Utah.